The objectives of the proposed research are to isolate from Compositae new compounds which have antitumor and other biological properties of potential medicinal value. Emphasis will continue to be placed on sesquiterpene lactones, many of which have exhibited cytotoxic and antitumor activity in the past , so that a wider spectrum of compounds for testing can be provided. The chemistry of the compounds will be studied in order to establish their structure. New compounds will be submitted to the antitumor screen of the Cancer Chemotherapy National Service Center and to other programs for drug evaluation. Since sesquiterpene lactones have shown promise as taxonomic markers, the results may also be useful for the clarification of phylogenetic relationships within Compositae.